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| 1 | Synchronous estimation of DTM and fractional vegetation cover in forested area from airborne LIDAR height and intensity data显示文摘We proposed a method to separate ground points and vegetation points from discrete return,small footprint airborne laser scanner data,called skewness change algorithm.The method,which makes use of intensity of laser scanner data,is especially applicable in steep,and forested areas.It does not take slope of forested area into account,while other algorithms consider the change of slope in steep forested area.The ground points and vegetation points can be used to estimate digital terrain model(DTM) and fractional vegetation cover,respectively.A few vegetation points which were classified into the ground points were removed as noise before the generation of DTM.This method was tested in a test area of 10000 square meters.A LiteMapper -5600 laser system was used and a flight was carried out over a ground of 700―800 m.In this tested area,a total number of 1546 field measurement ground points were measured with a total station TOPCON GTS-602 and TOPCON GTS -7002 for validation of DTM and the mean error value is -18.5 cm and the RMSE(root mean square error) is ±20.9 cm.A data trap sizes of 4m in diameter from airborne laser scanner data was selected to compute vegetation fraction cover.Validation of fractional vegetation cover was carried out using 15 hemispherical photographs,which are georeferenced to centimeter accuracy by differential GPS.The gap fraction was computed over a range of zenith angles 10° using the gap light analyzer(GLA) from each hemispherical photograph.The R2 for the regression of fractional vegetation cover from these ALS data and the respective field measurements is 0.7554.So this study presents a method for synchronous estimation of DTM and fractional vegetation cover in forested area from airborne LIDAR height and intensity data. | BAO YunFei1,2,CAO ChunXiang1,ZHANG Hao1,CHEN ErXue3,HE QiSheng1,2,HUANG HuaBing1,LI ZengYuan3,LI XiaoWen1,4 & GONG Peng1 1 State Key Laboratory of Remote Sensing Science,jointly sponsored by the Institute for Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University,Beijing 100101,China 2 Graduate University of the Chinese Academy of Sciences,Beijing 100049,China 3 Institute of Forest Resource Information Technique,the Chinese Academy of Forestry,Beijing 100091,China 4 Research Center for Remote Sensing and GIS,Department of Geography and Beijing Key Laboratory for Remote Sensing of Environment and Digital Sites,Beijing Normal University,Beijing 100875,China | 2008 | Science China(Technological Sciences)2008，51，S2： | 10 |
| 2 | Monte Carlo simulation of phonon transport in variable cross-section nanowires显示文摘A dedicated Monte Carlo (MC) model is proposed to investigate the mechanism of phonon transport in variable cross-section silicon nanowires (NWs). Emphasis is placed on understanding the thermal rectification effect and thermal conduction in tapered cross-section and incremental cross-section NWs. In the simulations, both equal and unequal heat input conditions are discussed. Under the latter condition, the tapered cross-section NW has a more prominent thermal rectification effect. Additionally, the capacity of heat conduction in the tapered cross-section NW is always higher than that of the incremental one. Two reasons may be attributed to these behaviors: one is their different boundary conditions and the other is their different volume distribution. Although boundary scattering plays an important role in nanoscale structures, the results suggest the influence of boundary scattering on heat conduction is less obvious than that of volume distribution in NWs with variable cross-sections. | WANG Zan1, ZHAO RuiJie1 & CHEN YunFei1,2 1 Department of Mechanical Design, School of Mechanical Engineering, Southeast University, Nanjing 211198, China 2 Key Laboratory of MEMS of Ministry of Education, Southeast University, Nanjing 211198, China | 2010 | Science China(Technological Sciences)2010，53，2： | 1 |
| 3 | 显示文摘 | CAI Tiejun1 LIAO Yuchao2 PENG Zhenshan1 LONG Yunfei1 WEI Zongyuan1 DENG Qian1 1. College of Chemistry & Chemical Engineering Hunan University of Science & Technology Xiangtan 411201 China.2. Institute of Process Engineering Chinese Academy of Sc | 2009 | Journal of Environmental Sciences2009，，07： | 1 |
| 4 | Study on impurity desorption induced by femtosecond pulse laser based on a stochastic process model显示文摘With the advantages on non-equilibrium heating and desorption induced by electronic transition, the femtosecond pulse laser introduces a new way for solving the problem of impurity pollution adsorbed on a solid thin film in micro-electro-mechanical systems (MEMS). A model based on stochastic processes was established for stimulated desorption induced by the femtosecond pulse laser to interpret the interaction of the opti-cally excited hot electrons with the adsorbed molecules in a metal substrate. Numerical simulation results reveal a time-dependent desorption probability of adsorbed molecules and indicate that how key parameters of femtosecond pulse laser, such as incident laser energy flux, pulse duration, and wavelength of pulse, have a great effect on the desorption probability. | CHI Yinsheng1, LIN Xiaohui1, ZHUANG Ping1 & CHEN Yunfei1,2 1. Department of Mechanical Engineering, Southeast University, Nanjing 210096, China 2. Key Laboratory of MEMS of China Educational Ministry, Southeast University, Nanjing 210096, China | 2006 | Science China(Technological Sciences)2006，49，1： | 0 |
| 5 | Natural Ventilation of Modern Residences in Rural Area in Guangdong Meishan City of China显示文摘By taking a modern residence in Meishan area as an example,15 measuring points have been set,and the wind speed of the parlor on the first and second floor and that of many bedding rooms have been measured every other hour from 7:00 to 22:00.Based on the measuring data and indoor architectural pattern,indoor ventilation has been analyzed.The results show that good natural ventilation could be created in modern rural residence by making use of plane layout,orientation and openings' organization,so that indoor air can be distributed evenly,helping to reduce temperature and remove humidness;indoor wind speed of the openings of architectures is the largest;and architectural orientation and opening's position can guide air flow and help to improve natural ventilation obviously. | GAO Yunfei1,2,CHEN Yunxi1(1.College of Architecture and Urban Planning,Guangdong University of Technology,Guangzhou,Guangdong 510090,China 2.State Key Laboratory of Subtropical Building Science of South China University of Technology,Guangzhou,Guangdong 510614,China) | 2012 | Journal of Landscape Research2012，4，7： | 0 |
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